  ; that has every child of a parent-link in its ancestor-set. 
 ; Or, more simply, variables should "die off".  
 ;; TODO: generalize.  This is just special case for most logistics.
-(defn dead-end? [s ancestor-map child-map extra-edges]
+(defn uses-dead-vars? [s ancestor-map child-map extra-edges]
 ;  false #_
   (let [gpm      (:precond-map (state/get-var s (action-var sas/goal-var-name)))
         live-set (apply clojure.set/union #{sas/goal-var-name}

           simple-dtgs   (util/map-vals (fn [dtg] (for [[pval emap] dtg, [eval _] emap] [pval eval])) dtgs)
           acyclic-succ-fn (partial possibly-acyclic-successors (HashMap.) simple-dtgs)]
       (assert (graphs/dag? causal-graph))    
                                        ;    (clojure.inspector/inspect-tree child-var-map)
       (ASPlanEnv.
        sas-problem
        (expand-initial-state (env/initial-state sas-problem) child-var-map (goal-action dtgs))

          :naive (make-fire-action (->> effect-var action-var (state/get-var s)))
          :greedy (make-greedy-fire-action s effect-var)
          (:sloppy :extra-sloppy) (make-sloppy-fire-action s effect-var))
     #_ (-> (env/applicable? s) assert)))



